Ballistic attack and knife stab are the two major threats against human bodies. Usually, it is impossible for individual defenders to predict the coming threat is a ballistic attack or a knife stab. In this case, a single equipment with both stab and ballistic resistant functions is very necessary. Nevertheless, the mechanisms of stab resistance and ballistic resistance are quite different, so it is very difficult for a material to possess both of these two functions.
Some researchers have explored the penetration of P knife (see Textile Research Journal vol 76 (8) 607-613), indicating that an acuminous knife point exerts an extremely strong penetrating power and a sharp knife blade exerts an extremely strong cutting power to a material. In view of the above, investigation was carried out on the basis of the following two aspects.
1) Defense against penetration of an acuminous knife point: for example in US2004/0048536A1 and U.S. Pat. No. 6,586,351B1, a high strength fabric adhered a coating of solid rigid particles was proposed to defend knife points.
2) Defense against incision of a sharp knife blade: for instance in U.S. Pat. No. 5,472,769, U.S. Pat. No. 5,736,474A and WO2002/007347A1, a structure mixed by fabric and wire netting or a strand structure twisted from stainless steel threads was proposed to defend incision of a sharp knife blade; in U.S. Pat. No. 6,280,546, fabric with a thermoplastic membrane adhered to its surface was proposed to improve the material's ability for cut-resistance.
However the processes described above, as a whole, have poor effects, and lack of ballistic resistant function.
Dupont Co. proposed, in U.S. Pat. No. 6,475,936B1, to use a fabric loosely woven from aramid yarn with broken crow satin weave as a stab-resistant layer, and to use the plain weave fabric tightly woven from low denier aramid yarn as a ballistic resistant layer. Overlap of these two layers can achieve both stab and ballistic resistant properties, but such stab and ballistic resistant material has not been accepted by the market, due to the high cost of the weaving technique and low denier yarn.
Honeywell Int. proposed, in WO2007/084104A2, a stab-resistant layer material composed of multilayers of HSHM-PE fabric and rubber. The overlap of multilayers of Honeywell LCR UD is used as a ballistic resistant layer material. Overlap of the above two materials can achieve both stab and ballistic resistant properties. However the processing of the stab-resistant layer of such material is very difficult to be industrialized.